1. Field of the Invention
The invention relates to a steam-cooled gas turbine and, in particular, to an arrangement for sealing spindle bolts of a steam-cooled gas turbine.
2. Description of the Related Art
In order to improve the efficiency of a gas turbine, the temperature of the combustion gas at the inlet of the gas turbine has recently been increased to 1,500 degrees Celsius. In order to protect the stator and the blades from the high temperature combustion gas, a so-called steam-cooled gas turbine, in which these elements are cooled by relatively low temperature steam, is under development. In such a steam-cooled gas turbine, steam is supplied from a steam source such as, for example, a steam extracting pipe in a steam turbine in a combined cycle or in an auxiliary boiler. In particular, the steam for cooling the blades of a gas turbine is supplied from a steam source through a steam passage formed to extend through the rotor to the respective blades fixed to the rotor.
The steam passage includes a plurality of steam supply passages longitudinally extending in the rotor from its tail end, an annular steam supply chamber, which is fluidicly connected to the plurality of steam supply passages, for distributing the steam equally to the respective blades, a steam recovery chamber for receiving the steam equally from the blades, and a plurality of steam recovery passages for directing steam from steam recovery chambers to the outside of the steam-cooled gas turbine.
FIG. 14 is a partial section of a rotor of a steam-cooled gas turbine according to a prior art turbine and shows first and second rotor disks 110 and 120 of a rotor 100. The disks 110 and 120 include a plurality of longitudinally extending spindle bolt holes 112 and 122 which are circumferentially arranged at intervals. The first and second rotor disks 110 and 120 are connected together with the other rotor disks (not shown) of the gas turbine by spindle bolts 102 inserted through the holes 112 and 122 so as to provide the integral rotating rotor 100 of the steam-cooled gas turbine.
The first and second rotor disks 110 and 120 further include a plurality of steam passages 114 and 124, circumferentially arranged at intervals, for supplying and recovering the steam for cooling the blades. The steam passages 114 and 124 are disposed in the peripheral portions of the rotor disks 110 and 120 radially outside of the holes 112 and 122. A plurality of steam supply conduits 104, which provide a steam supply passage for supplying the steam to the blades, and a plurality of steam recovery conduits 106, which provide a steam recovery passage for directing the steam used for cooling the blades to the outside of the steam-cooled gas turbine, are circumferentially alternatively provided in the steam passages 114 and 124.
A steam supply chamber 130, for equally distributing the steam to the primary blades (not shown), which are attached to the first rotor disk 110, is formed in the axially outer end face of the first rotor disk 110. A steam recovery chamber 132, for equally receiving the steam used for cooling the primary and secondary blades, is formed between the first and second rotor disks 110 and 120. Likewise, a steam supply chamber 134 for equally distributing the steam to the secondary blades is formed between the second rotor disk 120 and a third rotor disk (not shown).
In general, extracted steam from a low pressure steam turbine is used as cooling steam. The steam is supplied to the steam supply conduits 104, from which the steam is further supplied to the primary and secondary blades through the steam supply chambers 130 and 134. The steam used for cooling the primary and secondary blades is received by the steam recovery chamber 132 from which the steam is directed to the outside of the steam-cooled gas turbine through the steam recovery conduits 106.
The spindle bolt holes 112 and 124 have a diameter which is larger than the outer diameter of the spindle bolts to ensure the workability of assembly of the rotor by connecting the rotor discs to each other by spindle bolts. Therefore, relatively large gaps result between the spindle bolt holes and the spindle bolts. On the other hand, the steam recovery chambers 132 and 134 which are formed in the rotor are fluidly connected to the spindle bolt holes 112 and 122 so that steam leaks through the gaps between the first and second rotor discs 110 and 120 and the spindle bolts 102 result. The steam leakage through the gaps between the secondary rotor disc 120 and the spindle bolts 102 flows into the steam recovery chamber 132 so that it can be recovered through the steam recovery conduits 106. However, the steam leakage through the gaps between the first rotor disc 110 and the spindle bolts 102 cannot be recovered, which decreases the overall efficiency of a plant which utilizes the steam-cooled gas turbine.
In order to reduce the steam leakage through the gaps between the first rotor disc 110 and the spindle bolts 102, in the prior art, for example Japanese Unexamined Patent Publication No. 11-50803, annular sealing members 140, as shown in FIGS. 14 and 15, are provided. Snap rings 142 are used as a fastener for securing the sealing members 140 to the first rotor disk 110. The snap rings 142 are fitted in grooves 116 which are formed in the first rotor disc 110. When the rotor rotates, the centrifugal force applied thereto results in deformations in the respective snap rings 142, which in particular reduces the diameter of the snap rings 142, which may result in detachment of the snap rings 142 from the grooves 116.
As shown in FIG. 14, the steam supply chamber 130 is provided at one of the ends of the rotor 100, which end is disposed in the central portion of the steam-cooled gas turbine. The steam leakage from the steam supply chamber 130 may result in a problem of condensation around the bearings in the central portion of the steam-cooled gas turbine. Therefore, a severe sealing arrangement around the steam supply chamber 130 is required. Further, in order to allow inspection or the execution of maintenance in the steam supply chamber 130, a simple sealing arrangement is desired.
The invention is directed to solve the prior art problems, and to provide a steam-cooled gas turbine improved to prevent the detachment of the fastener.
Another objective of the invention is to provide an arrangement for sealing or reducing the steam leakage through the gap between the first rotor disk and the spindle bolts, which arrangement is improved to prevent the detachment of the fastener for securing the sealing members to the first rotor disk.
Another objective of the invention is to provide a method of assembling such steam-cooled gas turbine.
Another objective of the invention is to provide a steam-cooled gas turbine which includes a steam chamber closed by a closure which can be assembled easily.
The invention provides a steam-cooled gas turbine with a plurality of blades cooled by steam supplied from an external steam source. The steam-cooled gas turbine has a rotor for supporting the blades. The rotor is composed of a plurality of rotor disks which includes a plurality of spindle bolt holes circumferentially arranged at intervals and spindle bolts extending through the spindle bolt holes to connect the plurality of rotor disks to each other to define the rotor. The rotor includes a steam supply passage extending in the rotor, a steam supply chamber, fluidly connected to the steam supply passage and the respective blades, for distributing the steam to the respective blades from the steam source through the steam supply passage, a steam recovery chamber, fluidly connected to the respective blades, for equally receiving the steam used for cooling the blades, and a steam recovery passage, fluidly connected to the steam recovery chamber, for directing the steam from the steam recovery chamber to the outside of the steam-cooled gas turbine. A sealing member substantially in the form of a ring, for sealing the steam leakage between the rotor and the spindle bolts, is disposed about each of the spindle bolts. The rotor disk includes recesses, disposed coaxially with the respective spindle bolt holes, for receiving the sealing members. Each of the recesses has an annular bottom wall and an inner wall connected to the bottom wall. The inner wall has a diameter larger than that of the spindle bolt hole. A plurality of holding members holds the sealing members in place within the respective recesses by axially clamping the sealing members and engaging with the inner walls of the recesses.
According to another feature of the invention, there is provided an arrangement for sealing between spindle bolts and a rotor of a steam-cooled gas turbine. The steam-cooled gas turbine has a plurality of blades cooled by steam, and a rotor for supporting the blades. The rotor is composed of a plurality of rotor disks which includes a plurality of spindle bolt holes circumferentially arranged at intervals and spindle bolts extending through the spindle bolt holes to connect the plurality of rotor disks to each other to define the rotor. The rotor includes a steam supply passage extending in the rotor, a steam supply chamber, fluidly connected to the steam supply passage and the respective blades, for distributing the steam to the respective blades from the steam source through the steam supply passage, a steam recovery chamber, fluidly connected to the respective blades, for equally receiving the steam from the respective blade used for cooling the blades, and a steam recovery passage, fluidly connected to the steam recovery chamber, for directing the steam from the steam recovery chamber to the outside of the steam-cooled gas turbine. The arrangement has a sealing member in the form of substantially a ring, disposed about the respective spindle bolts, for sealing the steam leakage between the rotor and the spindle bolts. The rotor includes recesses, disposed coaxially with the respective spindle bolt holes, for receiving sealing members, each of the recesses having an annular bottom wall and an inner wall connected to the bottom wall, the inner wall having a diameter larger than that of the spindle bolt hole. A plurality of holding members holds the sealing members in place within the respective recesses by axially clamping the sealing members and engaging with the inner walls of the recesses.
According to another feature of the invention, there is provided a method of assembling an arrangement for sealing between spindle bolts and a rotor of a steam-cooled gas turbine. The steam-cooled gas turbine has a plurality of blades cooled by a steam, and a rotor for supporting the blades. The rotor is composed of a plurality of rotor disks which includes a plurality of spindle bolt holes circumferentially arranged at intervals and spindle bolts extending through the spindle bolt holes to connect the plurality of rotor disks to each other to define the rotor. The rotor includes a steam supply passage extending in the rotor, a steam supply chamber, fluidly connected to the steam supply passage and the respective blades, for distributing the steam to the respective blades from the steam source through the steam supply passage, a steam recovery chamber, fluidly connected to the respective blades, for equally receiving the steam from the respective blade used for cooling the blades, and a steam recovery passage, fluidly connected to the steam recovery chamber, for directing the steam from the steam recovery chamber to the outside of the steam-cooled gas turbine. The method includes the steps of disposing annular sealing members about the respective spindle bolts to abut the bottom walls of the respective recesses; disposing first holding members within the respective recesses from the axially outside of the sealing members to abut the sealing members; disposing fastener members between the respective first holding members and the recesses; disposing second holding member within the respective recesses from the axially outside of the fastener members to axially clamp the fastener members together with the first holding members.
According to another feature of the invention, there is provided a steam-cooled gas turbine with a plurality of blades cooled by steam supplied from an external steam source. The steam-cooled gas turbine has a rotor for supporting the blades. The rotor is composed of a plurality of rotor disks which includes a plurality of spindle bolt holes circumferentially arranged at intervals and spindle bolts extending through the spindle bolt holes to connect the plurality of rotor disks to each other to define the rotor. The rotor includes a steam supply passage extending in the rotor, a steam supply chamber, fluidly connected to the steam supply passage and the respective blades, for distributing the steam to the respective blades from the steam source through the steam supply passage, a steam recovery chamber, including an annular recess defined in the high pressure side end face of the rotor to be fluidly connected to the respective blades, for equally receiving the steam from the respective blade used for cooling the blades, and a steam recovery passage, fluidly connected to the steam recovery chamber, for directing the steam from the steam recovery chamber to the outside of the steam-cooled gas turbine. A catch in the form of radially outwardly extending portions is integrally connected to the rotor to be arranged alternatively along substantially the inner periphery of the opening of the annular recess. A closure in the form of substantially a ring is provided for closing the opening of the annular recess. An engaging portion in the form of radially inwardly extending portions alternatively is arranged along the inner periphery of the closure. The closure is attached to the rotor by the engagement between the catch and the engaging portions.